ive done all the quests for phase diving but i still cant dive am i missing a quest or something already did the another world quest line havent been able to dive once on my main character and none of my other characters are high enough leveled
According to DataforAzeroth, you have not done the Phase Diving quests yet.
Try picking up the below quest.
https://www.dataforazeroth.com/characters/US/Hyjal/Ceremalairn/quests